DM9161CI DAVICOM [Davicom Semiconductor, Inc.], DM9161CI Datasheet - Page 19

• Manufacturer Part Number: DM9161CI
• Description: Industrial-Temperature 10/100 Mbps Fast Ethernet Physical Layer Single Chip Transceiver
• Manufacturer: DAVICOM [Davicom Semiconductor, Inc.]

7.2.2 100Base-TX Receiver
The 100Base-TX receiver contains several function blocks
that convert the scrambled 125Mb/s serial data to
synchronous 4-bit nibble data, which is then provided to the
MII.
The receive section contains the following functional blocks:
- Signal Detect
- Adaptive Equalizer
- MLT-3 to NRZI Decoder
- Clock Recovery Module
- NRZI to NRZ Decoder
- Serial to Parallel
- Descrambler
- Code Group Alignment
- 4B5B Decoder
7.2.2.1 Signal Detect
The signal detects function meets the specifications
mandated by the ANSI XT12 TP-PMD 100Base-TX
Standards for both voltage thresholds and timing
parameters.
21
Binary
In
D
Binary
MLT-3
CK
.
In
Q
Q
10/100 Mbps Fast Ethernet Physical Layer Single Chip Transceiver
.
Binary minus
Binary plus
Figure 7-4
7.2.2.2 Adaptive Equalizer
When transmitting data at high speeds over copper twisted
pair cable, attenuation based on frequency becomes a
concern. In high speed twisted pair signaling, the frequency
content of the transmitted signal can vary greatly during
normal operation based on the randomness of the
scrambled data stream. This variation in signal attenuation
caused by frequency variations must be compensated for to
ensure the integrity of the received data. In order to ensure
quality transmission when employing MLT-3 encoding, the
compensation must be able to adapt to various cable
lengths and cable types depending on the installed
environment. The selection of long cable lengths for a given
implementation requires significant compensation, which will
be over-kill in a situation that includes shorter, less
attenuating cable lengths. Conversely, the selection of short
or intermediate cable lengths requiring less compensation
will cause serious under-compensation for longer length
cables. Therefore, the compensation or equalization must
be adaptive to ensure proper conditioning of the received
signal independent of the cable length.
7.2.2.3 MLT-3 to NRZI Decoder
The DM9161CI decodes the MLT-3 information from the
Digital Adaptive Equalizer into NRZI data. The relation
between NRZI and MLT-3 data is shown in figure 7-4.
7.2.2.4 Clock Recovery Module
Common
driver
MLT-3
Version: DM9161CI-DS-F01
DM9161CI
February 22, 2012
Final